In this post to is site Andrew Smith refutes the misconception that version three (v3) of the Slim PHP microframework is "not so slim" anymore with some of the additions to this latest version, increasing it's size and complexity.
There is a common misconception that Slim 3 has plenty of files and is no longer slim. Slim 3 does indeed contain more files than Slim 2 and this has been the result of being more flexible and moving away from the Not Invented Here (NIH) philosophy.
Installing Slim 3 through composer will install all its dependencies, when doing a PHP file count you will notice we have doubled in file count. This is a given with the amount of flexibility we now have. Most developers might not see any benefit in this as they will likely just work with what is provided, but if at any point you should hit a limitation in any working part of the framework, you can easily swap it out without a fuss.
He includes the command to install this latest version via Composer and how to count the number of files with a single command. He points out that some people that are reporting 1000+ PHP files being installed with the framework are probably getting the development packages as well and not just the release. He points out that "Slim 3 is still slim, we just added more flexibility in it." He ends the post with a thanks to Josh Lockhart and a few others who have made large contributions to the project and have helped make it what it is.